1. Innere Medizin 2, Caritas Krankenhaus Bad Mergentheim, Germany
2. Gastroenterology, Hepatology and Endocrinology, Medizinische Hochschule, Hannover, Germany
3. Gastroenterology, University of Medicine and Pharmacy “Iuliu Hatieganu”, Institute for Gastroenterology and Hepatology “O.Fodor”, Cluj-Napoca, Romania